Load equalizing device for thrust bearings



Jan. 27, 1953 A. w. BURKS LOAD EQUALIZING DEVICE FOR THRusT BEARINGS Filed July 6, 1950 E/ gl 20 Arzhur W. Barks y] Lwz/QZQE Patented Jan. E?, 1953 LOAD EQUALIZING DEVICE FOR THRUST BEARINGS Arthur W. Burks, Decatur, Ill., assigner to Decatur Pump Company, Decatur, Ill., a corporation of Illinois Application July 6, 1950, Serial No. 172,234

E Claims.

The present invention relates to a load equalizing device for thrust bearings, and more particularly to means for individually apportioning the total thrust load imposed on a plurality of bearings. l

In various environments, as in machine tools and the like, the thrust load imposed on a rotary member is transmitted to a stationary housing or the like through a plurality of thrust bearings. One thrust race of each bearing is secured `to the relatively movable member and the other race of the bearing is xed with respect to the relatively xed member, The load imposed upon any one of the thrust bearing races should be predetermined in order to insure the provision of a suitable type and size bearing for the load which it must bear. However, the determination of the thrust load on a given bearing under these circumstances is extremely diicult due to the many factors of design and to the varying nature of the load imposed on the rotary member, and to many other factors involved in the specific installation.

The present invention now provides improved means for individually apportioning the thrust load upon a plurality of bearings so that a predetermined portion of the total thrust load will be imposed on each bearing. The present invention, thus contemplates, in elect, the provision of a coupling between the bearings for accommodating the predetermined division of thrust loads between a plurality of bearings. In this manner, the thrust load which is to be imposed upon a given bearing may be determined prior to bearing installation, thereby preventing the failure of the bearing under load and obviating `the necessity of carrying out the extremely complicated calculations heretofore necessary.

The means of the present invention are particularly adapted for employment in machine tools, such as routers and the like. The particular means of the present invention suitably include a generally cylindrical thrust collar confined between the stationary thrust race of a bearing and a stationary housing which journals the relatively rotatable member.

More particularly, the collar is in surface contact with a resiliently deformable, non-compressible reactance member conned within the xed housing for the rotary member. vTo apportion the load between the plurality of thrust bearings, each of the bearings is provided with a similar collar and each of the collars independently of the other, contacts a single reactance member, so that the total thrust load on the rotary member is exerted on the reactance member .through the medium of the collars. The total force transmitted to reactance member by any collar is directly proportional to the contacting surface area of ythe collar in comparison with thc total contacting area of all the collars. Thus, the portion of the thrust load to be transmitted to the housing through each of the bearings is dependent upon and directly proportional to the area of the collar of that bearing which contacts the reactance member.

It is, therefore, an important object of the present invention to provide an improved thrust load equalizing device for a plurality of thrust bearings, the device serving to apportion between a plurality of bearings the total thrust load imposed thereon.

Another important object of the present invention is to provide an improved load equalizing -device for a plurality of thrust bearings including the resilient reactance member capable of iiowing under load and means for transmitting from the bearings to the reactance member that portion of the load imposed on the bearings.

Another important object of the present invention is to provide a load equalizing device for a, plurality of thrust bearings including a flowable reactance member conned within a stationary housing and means connecting each of the bearings with ythe reactance member for transmitting from the bearings to the reactance member that load imposed on the bearing, said reactance member serving by a fluid flow to apportion the total load on the bearing between the individual bearings.

Still another important object of the present invention is to provide means for apportioning the total thrust load between a plurality of concentric thrust bearings, the means including cylindrical thrust collars for each of the bearings, and a reactance member in surface Contact with the collars, the reactance member being capable of flow under pressure to apporticn the total load between the bearings.

Other and further important objects of this invention will be apparent from ,the disclosures in the specication and the accompanying drawings.

On the drawings:

Figure 1 is a broken longitudinal axial sectional view, with parts in elevation, of the router spindle provided with a load equalizing device of the present invention;

Figure 2 is a fragmentary sectional view taken along theplane II-II 0f Figure 1; and

Figure 3 is fragmentary sectional view, similar to Figure 1 and illustrating a modified form of the device of the present invention.

As shown on the drawings:

In Figure 1, reference numeral I refers generally to a machine tool router, including a housing II having an axial bore I2. A router spindle I3 is mounted in the bore I2 to extend axially therethrough.

The spindle I3 is rotatably journalled in the bore I2 by suitable means, to be hereinafter more fully described. The spindle I3 is axially bored as at I4 to receive therethrough an elongated tie bolt I5. A tool I6 is provided with a head I1 projecting beyond the spindle I3 and with a rearwardly facing generally frusto-conical end portion I8 seated in a correspondingly axially apertured collar or chuck I9. The tool head I6 is retained in the chuck I9 by means of the tie bolt I5, which is threaded into the tool and is retained in the spindle by means of nuts threaded against the other end of the spindle from that receiving the tool I6.

At the end of the spindle I3 facing the cutting tool head I1 is an annular shoulder 2I against which is press-fitted a sealing or retaining ring 22 having an L-shaped cross section. The ring 22 is rotatable with the spindle I3. Freely fitted within the ring 22 is a retaining ring 23. The ring 23 is secured to the stationary housing I I by means of screws 24, of which one is illustrated.

The spindle I3 has a generally stepped configuration formed by portions having progressively increasing diameters with annular shoulders 25 and 3| therebetween and spaced apart from one another in a predetermined relationship. Seated on the shoulder 25 of the spindle I3 is an inner race 26 of a group of concentric thrust bearings 21 for journalling the spindle I3 in the bore I2 of the stationary housing II. The inner race 26 is secured to the spindle I3 and rotates therewith, while an outer race 28 remains stationary and is secured to the housing I I. Balls 29 are rotatable between the inner race 26 and the outer race 28.

A second group of concentric thrust bearing assemblies 30 are seated on the shoulder 3l for further journalling the spindle I3 in the bore I2 of the stationary housing I I. An inner race 32 is seated on the shoulder 3I. The inner race 32 is secured to the spindle I3 and rotates therewith. An outer race 33 remains stationary.

Confined between the stationary outer thrust race 28 of the thrust bearing 21 and the stationary housing II is a generally cylindrical thrust collar 34, which journals the rotatable spindle I3. A similar thrust collar is seated on the outer thrust race 33 in a confined relationship with# the thrust collar 34, and an outer sealing ange 36, as well as with the thrust collar 34. The thrust collars 34 and 35 are rigid non-compressible coupling members.

The thrust collars 34 and surface contact with a resiliently deformable, non-compressible reactance member or ring 31, which is confined between the sealing flange 36, the housing II and the thrust collars 34 and 35.

The reactance member 31 may be made of any' suitable resilient material, such as an oil-resistant rubber substitute, or elastomer, like neoprene, which flows to take up any inaccuracies in machine dimensions or any change due to temperature variations, or the member may be a noncompressible fluid.

To apportion the load, each group of thrust bearings, such as 21 and 30, is provided with a thrust collar. v Force is imparted from the thrust 35 are in extended' bearings 21 to the thrust collar 34 and further force is imparted from the thrust bearing 30 to the thrust collar 35. The thrust collar 34 and the thrust collar 35 contact a single reactance member, such as the neoprene ring 31, so that the total thrust load on the rotary member is exerted on the neoprene ring 31 through the medium of the thrust collars 34 and 35. The total thrust imposed on the reactance member 31 by the collars is the total thrust load imposed on the bearings 21 and 30 from the rotary member I3. The neoprene ring 31 transmits to the housing II the thrust load imposed thereon. The total force transmitted to the neoprene ring 31 by any collar is directly proportional to the contacting area of the collar in comparison with the total contacting area of all of the collars. Thus, the portion of the thrust load transmitted to the housing II through each of the bearings is dependent upon and directly proportional to contacting surface between the collar associated therewith and the reactance ring 31. Therefore, to equalize the thrust load for each bearing, the thrust collars must have equal cross sectional areas.

In the modified form, as shown in Figure 3, the cross sectional areas of the collar are not equal and therefore the thrust load for each thrust bearing is proportional to the respective cross sectional area of the collar associated therewith.

When assembling the spindle I3, all air or uid is removed from the neoprene chamber through the hole 38. A plug 39 is fitted into the hole 38 to seal the same.

A coolant or lubricating fluid is fed to the spindie assembly through an inlet 40 and the coolant passes therefrom into a passageway 4I and then through an outlet 42.

To further journal the spindle I3 in the bore I2, bearings 43 are provided. Bearings 43 are primarily rotational bearings for rotation of the spindle I3 relative to the stationary housing II. Springs 44 maintain the races of the bearings 43 in yaligned relation. A sealing ring 45 is shown fitted around the decreased diameter portion of the spindle I3.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

l. In .a machine tool router assembly, a plurality of thrust bearings, a spindle for exerting a rotary thrust on said bearings, a plurality of coupling members, each of said coupling members having a surface contact with a respective one of said thrust bearings for transmitting a thrust load therefrom, a housing member for absorbing the thrust load, and a non-compressible, flow'able reactance member having a predetermined surface contact area with each of said coupling members and said housing member through which the thrust load is transmitted from said coupling members to said housing member, whereby the thrust load for each of said bearings is proportional to the contact surface area of the coupling member associated therewith, said housing having a passage communieating with said reactance member from externally of the housing for removal of iiuid `adjacent to the reactance member, and means for closing said passage after removal of fiuid.

2. In a thrust bearing assembly including a housing having a bore providing an inner shoulder, -a shaft freely rotatable in said bore and having stepped annular shoulders facing said inner shoulder, and yanti-friction bearings including inner and outei' concentric radially aligned axially extending races, the inner races being seated in endwise abutment `against said stepped shoulders, the improvement whereby the thrust loads on said bearings are equalized comprising 'a saddle having `an end face seated against said inner shoulder and having in its opposite end face an annular groove, a noncompressible owable reactance member of annular shape seated in said saddle groove, and concentric axially extending coupling members each being at one end in endwse abutment With one of the outer bearing races `and at the other end being in endwise abutment with a portion of said reaetance member for imparting a thrust load thereto.

ARTHUR W. EURES.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,871,630 Minor Aug. 16, 1932 1,956,648 Messinger May 1, 1934 1,968,199 Greve July 31, 1934 

